This proposal represents a request to support continued participation in the pediatric Oncology Group (POG). This cooperative research is devoted to the investigation of chemotherapeutic, immunological and molecular biological approaches to the treatment of acute leukemia and other neoplastic diseases of childhood. Significant disease free survival has been achieved and contributions have been made in clinical pharmacology, tumor immunology and biology of cancer. However the real objective of these studies is the eradication of neoplastic diseases by treatment. Studies are being designed to reflect an increasing intensity of attack on the neoplastic cell. The cooperative group technique permits prompt evaluation in series of reasonable size of promising leads in chemotherapy. These leads or new approaches are often suggested by the results of the group's own work in clinical oncology. Thus, a completed protocol often suggests new avenues to be explored in new protocols. POG led in the investigation in the immunophenotyping of acute lymphoblastic leukemia, NTX polyglutamates accumulation in leukemic cells, and N-myc gene amplication in neuroblastoma, correlated the findings with patient outcome, and then incorporated them in new treatment protocols designed to improve the survival of children with cancer. The Division of pediatric Hematology/Oncology at the University of California, San Diego has 24 years experience (10 years in CALGB and 14 in POG) in cooperative clinical trials. In the past 5 years the 4 consortium member institutions had entered 332 patients on both therapeutic and non- therapeutic studies and the satellites, 211 patients. Our investigators served on 12 committees, designed/coordinated 16 group protocol studies. We also contributed to 15 group publications/presentations. Our investigators will continue to design and chair therapeutic protocols,and serve on committees. Dr. Yu's laboratory will continue to explore new immunotherapeutic agents for Group use, and serve as the Group Reference Laboratory. We plan to continue our active participation in all phases of POG activities.